1. Field of the Invention
The present invention relates to a deflection yoke, and more particularly, the present invention relates to a deflection yoke which improves picture dispersion due to assembling dispersion of a vertical deflecting coil and improves winding structures of the vertical deflecting coil and a horizontal deflecting coil.
2. Description of the Related Art
Generally, a deflection yoke used in a cathode ray tube (CRT) of a television receiver or a monitor is divided into a saddle-toroid type deflection yoke and a saddle-saddle type deflection yoke and functions to precisely deflect electron beams emitted from electron guns onto a fluorescent layer applied on a screen of a cathode ray tube.
In other words, as shown in FIG. 1, the conventional deflection yoke 10 is fitted around a neck part 2 of a cathode ray tube 1. As described above, the deflection yoke 10 is divided into a saddle-saddle type deflection yoke as shown in FIGS. 2 and 3 and a saddle-toroid type deflection yoke as shown in FIGS. 4 and 5, depending upon a winding structure of a coil thereof.
The deflection yoke 10 serves to horizontally and vertically deflect electron beams emitted from BGR electron guns 3 which are disposed in the neck part 2 of the cathode ray tube 1, thereby to precisely focus the electron beams onto a fluorescent layer of the cathode ray tube 1.
FIGS. 2 and 3 illustrate the conventional saddle-saddle type deflection yoke. As can be seen from FIGS. 2 and 3, in the saddle-saddle type deflection yoke, horizontal deflection coils 12 having a saddle-shaped configuration are disposed on upper and lower portions of a circumferential inner surface of a screen part of a coil separator 11 having a substantially frusto-conical configuration, and vertical deflecting coils 13 having a saddle-shaped configuration are disposed on left and right portions of a circumferential outer surface of the screen part of the coil separator 11.
A ferrite core 14 having a substantially cylindrical configuration is placed on the circumferential outer surface of the screen part of the coil separator 11, to reinforce a magnetic field of the vertical deflecting coils 13.
Also, coma-free coils 15 are arranged adjacent the circumference of the neck part of the coil separator 11, to compensate for coma which is generated by the vertical deflecting coils 13.
FIGS. 4 and 5 illustrate the conventional saddle-toroid type deflection yoke. As can be seen from FIGS. 4 and 5, in the saddle-toroid type deflection yoke, horizontal deflection coils 12 are disposed on upper and lower portions of a circumferential inner surface of a screen part of a coil separator 11 having a substantially frusto-conical configuration, a ferrite core 14 having a substantially cylindrical configuration is placed on a circumferential outer surface of the screen part of the coil separator 11, and vertical deflecting coils 16 having a toroid-shaped configuration are disposed on upper and lower portions of the ferrite core 14.
Further, coma-free coils 15 are additionally arranged adjacent the circumference of the neck part of the coil separator 11, to compensate for coma which is generated by the vertical deflecting coils 16.
Moreover, in the saddle-saddle type deflection yoke and the saddle-toroid type deflection yoke, a printed circuit board is positioned on a side of the coil separator 11, to supply power to the horizontal deflecting coils 12 and the vertical deflecting coils 13 and 16.
However, the conventional deflection yokes suffer from defects as described below.
In other words, in the process of coupling the ferrite core 14 around which the vertical deflecting coils 13 are wound, onto the circumferential outer surface of the coil separator 11 which has the horizontal deflecting coils 12 mounted onto the circumferential inner surface thereof, using a core clamp (not shown), the ferrite core 14 may be fluctuated due to its dimensional dispersion, winding dispersion of the vertical deflecting coil 13, etc. That is to say, the ferrite core 14 may be fluctuated on the coil separator 11 in a transverse or longitudinal direction even by a light impact.
As described above, if the ferrite core 14 around which the vertical deflecting coils 13 are wound, is fluctuated on the coil separator 11, because the vertical deflecting coils 13 cannot be precisely concentrically aligned with the coil separator 11, stable axial balance may not be ensured, whereby distortion is caused on a picture.
Namely, in the saddle-saddle type deflection yoke, there is caused a difference between the left magnetic field and the right magnetic field, due to relative dispersion and/or relative current amount between the left vertical deflecting coils and the right vertical deflecting coils, whereby mis-convergence and geometrical distortion (G/D) are generated on a picture.
Similarly to this, also in the saddle-toroid type deflection yoke, there is caused a difference between the left magnetic field and the right magnetic field, due to relative dispersion and/or relative current amount between the vertical deflecting coils 16 disposed on left upper and lower portions of the ferrite core 14 and the vertical deflecting coils 16 disposed on right upper and lower portions of the ferrite core 14, on X-Y axes, whereby mis-convergence and geometrical distortion (G/D) are generated on a picture.
The mis-convergence is divided into YV mis-convergence and YHC mis-convergence. The YV mis-convergence represents a vertical mis-convergence in which a transverse line of red color R is not in line with a transverse line of blue color B on upper and lower portions of Y axis as shown in FIGS. 6 and 7, and the YHC mis-convergence represents a horizontal misconvergence in which a longitudinal line of red color R is crossed with a longitudinal line of blue color B as shown in FIG. 8.
The geometrical distortion (G/D) represents a state in which a picture is not normal but distorted as shown in FIGS. 9 and 10 which specifically illustrate trapezoidal distortion of a picture.
In order to solve the problems occurring in the related art, as shown in FIG. 11, a plurality of elastic wedges 20 which are made of sponge, are attached on the circumferential outer surface of the coil separator 11 such that they are uniformly spaced apart one from another in a circumferential direction, to elastically bias outward the ferrite core 14 which is placed on the circumferential outer surface of the coil separator 11, whereby assembling dispersion is reduced to overcome the defects described with reference to FIGS. 2 through 10.
However, in the method for maintaining axial balance of the vertical deflecting coils 13 using the plurality of elastic wedges 20, because the elastic wedges 20 are deformed by themselves to a great extent, high dimensional precision cannot be accomplished, and according to this, dimensional dispersion is enlarged, whereby it is difficult to actually achieve the axial balance of the vertical deflecting coils 13.
Further, since the plurality of elastic wedges 20 are attached to the circumferential outer surface of the coil separator 11 by applying adhesive, attachment position varies relying upon a worker, by which attachment position dispersion is enlarged, whereby it is further difficult to stably achieve the axial balance of the vertical deflecting coils 13.
In addition, because the plurality of elastic wedges 20 are used, the number of components and cost are increased, and because the number of work steps including adhesive applying step for attaching the plurality of elastic wedges 20 is increased, workability and productivity are deteriorated.
Moreover, while one end and the other end of the horizontal deflecting coil 12 must be connected to the printed circuit board when it is disposed on the circumferential inner surface of the coil separator 11, because pick-off positions are close to each other, one end and the other end of the horizontal deflecting coil 12 may be brought into contact with each other due to an inadvertence of a worker thereby to cause a short and an electric shock, and in the course of connecting the vertical deflecting coils 13 and 16 to the printed circuit board, a short and an electric shock can be generated due to a contact between the horizontal deflecting coil 12 and the vertical deflecting coils 13 and 16.